How many HIV infections are there in Israel? Reconstructing HIV incidence from AIDS case reporting

Background: The reporting of AIDS cases to Israel's Ministry of Health is believed to be accurate, but the completeness of HIV surveillance is unknown. We implement a model that reconstructs HIV incidence in Israel from AIDS case reports excluding Ethiopian immigrants. Methods: We apply the well-known method of backcalculation to AIDS cases reported to the Ministry of Health. The data are adjusted statistically to account for reporting delays and the elimination of AIDS Related Complex reporting. The analysis also accounts for the impact of differential administration of antiretroviral therapy to HIV-infected persons over time. Results: Excluding Ethiopian immigrants, we find that the cumulative number of HIV infections reported to the Ministry of Health through December 1993 (1,011) is not statistically different from the model's estimate of 922 (z = 1.04; p = 0.30), though the reported number of new infections in recent years exceeds the modeleted rate. Conclusions: The low HIV incidence estimated among non-Ethiopian Israelis is consistent with other studies of sexually transmitted diseases and HIV-related risky behavior in Israel. This result counters the hypothesis that an explosive HIV epidemic will occur. That the number of recently reported new infections exceeds the estimate from the model could indicate that the reporting system is catching up with the extant spread of disease, or that the model is missing some aspect of the dynamics of HIV in Israel. We suggest that comparing future annual HIV incidence rates to the model's upper bound of 80 infections per year will enable resolution of this issue over time.